- Bubble sort, sometimes referred to as sinking sort, is a simple sorting algorithm that works by repeatedly stepping through the list to be sorted, comparing each pair of adjacent items and swapping them if they are in the wrong order. The pass through the list is repeated until no swaps are needed, which indicates that the list is sorted. The algorithm gets its name from the way smaller elements "bubble" to the top of the list. Because it only uses comparisons to operate on elements, it is a comparison sort. Although the algorithm is simple, most of the other sorting algorithms are more efficient for large lists.
Step-by-step example[edit]
- Let us take the array of numbers "5 1 4 2 8", and sort the array from lowest number to greatest number using bubble sort. In each step, elements written in bold are being compared. Three passes will be required.First Pass:
( 5 1 4 2 8 )( 1 5 4 2 8 ), Here, algorithm compares the first two elements, and swaps since 5 > 1.
( 1 5 4 2 8 )
( 1 4 5 2 8 )
( 1 4 2 5 8 )
Second Pass:
( 1 4 2 5 8 )
( 1 4 2 5 8 )
( 1 2 4 5 8 )
( 1 2 4 5 8 )
Now, the array is already sorted, but our algorithm does not know if it is completed. The algorithm needs one whole pass without any swap to know it is sorted.
Third Pass:
( 1 2 4 5 8 )
( 1 2 4 5 8 )
( 1 2 4 5 8 )
( 1 2 4 5 8 ) - DYNAMIC MEMORY ALLOCATION :=
when the the memory needs of a program can only be determined during runtime,this is called dynamic memory allocation.
For example, when the memory needed depends on user input. On these cases, programs need to dynamically allocate memory, for which the C++ language integrates the operators
new and delete.
THE PROGRAM WRITTEN BELOW IS SELF TESTED AND VERY TRUE.THE CODE IS GIVEN BELOW.
#include<iostream>
using namespace std;
void main()
{
int temp;
int n;
int *a; //pointer
cout<<"enter the size of array\n";
cin>>n;
a=new int[n]; //dynamic memory allocation
for(int z=0;z<n;z++) //get elements of array
{
cin>>a[z];
}
for(int i=1;i<n-2;i++) //compare and swap
{
for(int z=1;z<n;z++)
{
if(a[z]<a[z-1])
{
temp=a[z-1];
a[z-1]=a[z];
a[z]=temp;
}
}}
for(int z=0;z<n;z++) //display the array after comparing has been done
{
cout<<"\t"<<a[z];}
system("pause");
}
